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  • 1
    Electronic Resource
    Electronic Resource
    Evidence for element 109 from one correlated decay sequence following the fusion of58Fe with209Bi (1984)
    Springer
    The European physical journal 315 (1984), S. 145-158 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An experiment to synthesize element 109 is presented. Decay patterns characteristic of complete fusion products were searched for in an irradiation of209Bi targets with58Fe projectiles at specific incident energies of 4.95, 5.05, and 5.15 MeV/u. A total dose of 7 ×1017 particles was obtained. The experimental method involves in-flight separation of forward peaked reaction products with a static-field velocity filter, their passage through a time-of-flight device and their final implantation into position sensitive solid state detectors to measure their kinetic energy, approximate mass and their time and position of incidence. The subsequent decay of the narrowly localised reaction products by cascades of alpha particles and/or spontaneous fission is also registered in terms of the energies and times of all the emitted particles. One outstanding decay sequence that started with the emission of two alpha particles within subsequent time intervals of 5 ms and 22 ms and ended with spontaneous fission after 13 s was found at 5.15 MeV/u. The first alpha particle had a kinetic energy of (11.10±0.04) MeV. A detailed analysis of all the alternative interpretations of this observation, such as a purely random correlation of signals, the decay of a product from a transfer reaction or of any of the various energetically possible evaporation residues, shows that the isotope with mass 266 of element 109, i.e. the one neutron evaporation channel after complete fusion, is the statistically most significant assignment. The outlook for new element synthesis is also briefly discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01419373
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  • 2
    Electronic Resource
    Electronic Resource
    Element 107 (1989)
    Springer
    The European physical journal 333 (1989), S. 163-175 
    Details
    ISSN: 1434-601X
    Keywords: 23.60.+e ; 25.70.3f ; 25.85.Ca ; 27.9.+6
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We identified twoα-emitting isotopes of element 107 with masses of 261 and 262 respectively by parent-daughter correlations. For the isotope with mass 262 we found two transitions with (102±26) ms and (8.0±2.1) ms half-life, which we assign to the groundstate and to an isomeric transition, respectively. The half-life of the isotope with mass 261 is (11.8 −2.8 +5.3 ) ms. Spontaneous fission, which could be assigned to the decay of an isotope of element 107, was not detected in our experiments. This observation is in-line with our previous results, indicating a region of nuclei with strong microscopic stabilisation in the trans-actinides. Both new isotopes were produced by complete fusion of209Bi with54Cr. The production cross sections are (163±34) pb for262107 and (36 −14 +22 ) pb for261107.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01565147
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  • 3
    Electronic Resource
    Electronic Resource
    Alpha decay of new neutron deficient gold, mercury, and thallium isotopes (1983)
    Springer
    The European physical journal 312 (1983), S. 21-26 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In fusion evaporation reactions of a92Mo beam with targets of neutron deficient Rb — Mo isotopes very neutron deficient isotopes of elements between Au and Po have been produced. The new isotopes173, 174Au,175, 176Hg, and179Tl were identified by alpha spectroscopy. The mass excess value of176Hg could be linked to known values of theN−Z=16 chain. The location of the new isotopes with respect to the proton drip line is discussed. A new high energyα transition of (7.20±0.02) MeV andT 1/2=(1.4±0.5) ms has been found in the reaction92Mo+89Y→181Tl* at an excitation energy of 37 MeV. It is tentatively assigned to isotopes produced in 2-particle evaporation channels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01411657
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  • 4
    Electronic Resource
    Electronic Resource
    Proton radioactivity of151Lu (1982)
    Springer
    The European physical journal 305 (1982), S. 111-123 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A (1231±3) keV proton activity has been observed in the fusion reaction58Ni +96Ru→154Hf*. The production cross section peaks at 50 MeV of excitation energy with a value of about 70 μb. No coincidences with annihilation radiation or withK X-rays could be observed. The activity is assigned to direct proton decay of the new isotope151Lu. The measured half life is (85±10) ms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01415018
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  • 5
    Electronic Resource
    Electronic Resource
    The new isotopes258105,257105,254Lr and253Lr (1985)
    Springer
    The European physical journal 322 (1985), S. 557-566 
    Details
    ISSN: 1434-601X
    Keywords: 23.60.+e ; 25.85. Ca ; 25.70. Jj ; 27.90.+b
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Evaporation residues from the heavy-ion fusion reaction50Ti on209Bi were investigated. They were separated from the projectile beam by the velocity filter SHIP and identified after implantation into an array of position-sensitive surface-barrier detectors by analyzing theirα-decay chains. Spontaneous fission was also observed. Four newα emitters,258105 (T1/2=4.4 −0.6 +0.9 s),257105 (T1/2= 1.4 −0.3 +0.6 s),254Lr (T 1/2= 13 −2 +3 s), and253Lr (T 1/2=1.3 −0.3 +0.6 s) could be identified. For the isotope257105 we obtained a spontaneous-fission branch of about 20%. A spontaneous-fission activity with a halflife comparable to that for theα decay of258105 was explained as fission of258104, formed by electron capture from258105. An excitation function for evaporation-residue production was measured for bombarding energies in the range ofE CM=184.4 MeV toE CM=196.6 MeV. Nearly all evaporation residues we observed, could be attributed to the 1n and 2n deexcitation channels. The maximum cross sections wereσ(1n)=c/2.9±0.3) nbarn, andσ(2n)=c/2.1±0.8) nbarn, respectively. We could measure the total kinetic energy of the fission fragments of258104 to be TKE=(220±15) MeV, a value that fits into empirical systematics based on aZ 2/A 1/3 dependence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01415134
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